Coma vs. Brain death
- coma = not awake and not aware
- but, could still have spinal and brainstem reflexes preserved but still in coma
- brain dead is death by neurologic criteria
- time course for chronic phase/using “vegetative state” term
- persistent vegetative state = 1 mo timecourse
- 3 mo for non-trauma; 12 mo for trauma
Spectrum of cognitive and motor fxn
- Bernat et al Annu Rev Med 2009 -> what is death/consciousness
- spectrum -> conscious state vs. motor fxn
- purposeful interaction with the world
- vegetative state (APPLICABLE TO CHRONIC STATES/not ICU pts)
- coma
Covert / functional locked in syndrome
- adaptive tech is able to pick up their yes/no paradigms despite looking like they’re completely locked-in
- they have awareness of the world around them
- fMRI for example could be the adaptive tech that shows you’re able to interact w/ the world
Death (multiple different definitions)
- legal
- ethical
- medical
- biophysical -> cessation of critical fxn of the organism as a whole
Ventilator and ECMO has changed the way we view death
- b/c can have devastating neuro injury but pt is still alive via vent; so concept of brain death didn’t come up until 1950s/when vents were invented
Brain death <- remember full brain death differs from usual death exam (central/peripheral pulse, lack of respirations)
- functional imaging is changing the paradigm
- binary definition; never “brain dead, except…”
- should have a local policy at specific hospital you work at
- variation in the types of exam and the time course between exams
- not emergent; but, it is urgent
- not optional to do the brain death test
- CA law may have part where family can object? but, usually it is not optional.
- “whole brain” vs. “brainstem” death
- no universal definition unfortunately in society
- whole = demonstrate that entire brain is NOT fxn’ing
- brainstem = demonstrate that brainstem is out and not coming out -> brainstem could be out (i.e. brainstem stroke) with EEG activity on the cortex
- in the US you have to investigate the other areas of the brain -> if they have massive pontine and cerebellar hemorrhage, you still need to do EEG to interrogate the cortex (i.e. the rest of the brain)
- interestingly, as clearly not ALL the cells are dead
- can say to families “irreversible brain damage” or your family has “brain damage”
- AVOID term of BRAINDEAD unless you’re absolutely sure
Strict criteria
- complete cessation of neuro fxn
- cerebral circ arrest
- testing for brain death is not optional, but in CA, the family can refuse
- generally, a clinical diagnosis -> though ancillary testing can be performed ONLY if unable to declare clinically
Obstacles to brain death exam
- lytes
- e.g. of cannot perform brain death exam: cannot tolerate the apnea test (i.e. Hirsch’s first pt as attending, she put a CVICU pt on T-piece and the pt coded); cervical cord injury (you don’t know if that circuit is intact); in trauma pt missing an eye
- severe c spine injury or max/face injury <- precluding exam
- temp
- severe pCO2 acidemia
Nuclear perfusion test <- this is the test of choice at Stanford
- glucose labeled; injected at the bedside; come back 1h later and see if cerebral uptake (if uptake, then it’s not brain death); take picture of the head at bedside with nuclear imaging device (?specifically, unclear)
- tracer takes time to obtain
- it’s on California Ave
EEG -> has to be done in a specific way
cerebral angiogram -> looking for cessation of flow; this is gold standard at time of this lecture for “ancillary testing”
- inject and you see vessel fill but then should see blood flow stop
- it’s hard practically to do this b/c have to get cath lab study
TCDs <- unreliable; we don’t really use them
evoked potentials (peripheral stimulation) -> not validated for brain death; used for prognostics
Brain death exam (https://www.pathlms.com/ncs-ondemand/courses/1223)
- need a cause
- exclude confounding factors -> tox/temp, HD, uremia, hepatic failure, facial/c spine trauma, NMB
- this one is very important; unfortunately, this part of confounding factors is under constant debate -> e.g., how many half-lives should you wait for certain drugs on board (Stanford’s policy is 5 half-lives of a medicine; things like barbituates take a long, long time)
- do brain death exam/cranial nerves -> by two teams 1h apart; only one may need apnea test (usually, the second test is done w/ apnea exam)
- licensed MD with experience and comfort doing the brain death exam
- the other exam must be done by the neurology or NSGY attending
Steps to Hirch’s brain death exam (temp > 36C and SBP > 100 mmHg)
- MAR/med review
- normothermia (core should be > 36C); adequate BP (SBP > 100 mmHg)
- document cause
- document that not triggering vent -> turn down/off the backup rate and that pt not overbreathing the vent (do if you’re not worried that they’re not dangerously hypoxic)
- document there’s no HR or BP change w/ pain
- document no motor response w/ central/peripheral pain
- peripheral pain; central pain
- No response (other than spinal cord response) to painful stimuli in all 4 limbs
- cranial nerves:
- pupils via pupillometer
- cold calorics in one ear; then wait 5 min until the next ear (use small angiocath) <- don’t worry about COWS mnemonic; just make sure eyes don’t move
- corneal reflexes absent
- oculocephalics/doll’s eyes
- no cough/gag on deep suctioning
- no grimace to supraorbital nerve or TMJ
- apnea test
- Normal PCO2 -> Then, disconnect the vent
- Should have absent spontaneous respirations for time long enough for PCO2 to get 60 mmHg or 20 mmHg from baseline
- *on ECMO, turn down sweep and turn down the ventilator; can run oxygen down the tube just to avoid dangerous hypoxia; usually though, ECMO pts get ancillary tests too to test brain death
- ABG at 7 min
Donation after brain death
Donation after Circulatory Death (DCD) -> end stage disease and you’re planning to withdraw care; expectation that pt will die within 1h after withdrawal
*“thank you for bringing it up; in situations ilke this, there is a separate team that will d/w you about organ donation; they are separate from our team; when you are ready, i will step out and they can talk with you”
*ethics consult should be pursued for DCD cases <- end-stage disease where you’re thinking about care withdrawal
- usually age < 60 for DCD cases
*”it’s very kind of you to be thinking of other people during this time, we will gather the appropriate info; in the meantime i encourage you to process the info we just provided and we’ll follow up with you soon”
